1. Field of the Invention
The present invention relates to a ruthenium-BINAP (Ru-BINAP) asymmetric hydrogenation catalyst and, more particularly, relates to an asymmetric hydrogenation catalyst represented by the formula: EQU [RuXY(BINAP].sub.n
wherein n is an integer of from 1 to about 10.
2. Related Art
It is known to utilize certain Ru-BINAP complexes as catalysts for asymmetric hydrogenation reactions. For example, U.S. Pat. No. 4,691,037 discloses Ru-BINAP complexes, useful for asymmetric hydrogenations, which have the formulas: EQU Ru.sub.2 Cl.sub.4 (BINAP).sub.2 S EQU RuHClBINAP).sub.2
wherein S represents a tertiary amine. BINAP refers to the optically active forms of BINAP and T-BINAP. These catalysts are prepared by reacting [RuCl.sub.2 (COD)].sub.n (COD=cyclooctadiene), BINAP (2,2'-BIS(DIPHENYLPHOSPHINO)-1,1'-BINAPHTHYL), T-BINAP (p-Tolyl BINAP) or p-t-Butyl-BINAP, in the presence of a tertiary amine and in a solvent such as toluene or ethanol. See also, U.S. Pat. No. 4,962,230 wherein various other Ru-BINAP complexes are disclosed as being useful in asymmetric hydrogenation reactions.